I'll tell you anyway.... Yoghurt is full of good bacteria that is non-harmful, but if added to a warm damp place the bacteria multiplies and grows to fungus. Remember to keep whatever in you're growing in a large airtight container.
I once saw the Venus De Milo in some pudding I was eating. I took a picture but the flash kept making it disappear LOL Then I found a potato chip with a sad face on it. I ate it. It was delicious.